The coloring of photographic emulsion layers or other layers is often carried out in silver halide photographic light-sensitive materials in order to absorb light of a specified wavelength.
When it is necessary to control the spectral composition of the light which should be incident on a photographic emulsion layer then a colored layer is positioned on the side of a photographic emulsion layer that is farthest from the support in the photographic light-sensitive material. Such a colored layer is known as a filter layer. In cases where there is a plurality of photographic emulsion layers, as in the case of a multi-layer color light-sensitive material, then filter layers may also be located between these layers.
Colored layers can also be established between the photographic emulsion layer and the support or on the opposite side of the support from that of the photographic emulsion layer, in order to prevent image blurring which is caused by scattered light produced when passing through a photographic emulsion layer or transmitted reflected by the interface between the emulsion layer and the support or reflected at the surface of the light-sensitive material on the opposite side of the emulsion layer and redirected into the photographic emulsion layer, the above scattered light prevention thereby preventing halation. Colored layers of this type are known as anti-halation layers. Antihalation layers can also be established between the various layers in the case of a multi-layer color light-sensitive material.
Moreover, colored layers are also provided in X-ray light-sensitive materials as cross-over cut filters for reducing the amount of cross-over light in order to increase the level of sharpness.
The coloration of photographic emulsion layers is also carried out in order to prevent any reduction in image sharpness due to light scattering within the photographic emulsion layer (this phenomenon is known generally as irradiation).
These layers which are to be colored in many cases comprise a hydrophilic colloid layer and so dyes are normally included in the layers in order to achieve the desired coloration. The dyes used must at least satisfy the following conditions:
(1) they must have a spectral absorption which is suitable for their intended use;
(2) they must be photographically inactive, i.e., they must have no adverse chemical effects on the performance of the silver halide photographic emulsion layer, such as reduction of photographic sensitivity, latent image regression or fogging; and
(3) they must be decolorized and/or dissolved out and removed from the photographic material during the course of the photographic processing operations, without deleterious coloration remaining in the photographic light-sensitive material after processing.
Much work has been carried out by those in this field in order to find dyes which satisfy these conditions and include the following known dyes. For example, there are oxonol dyes which have a pyrazolone nucleus or a barbituric acid nucleus disclosed, for example, in British Patents 506,385, 1,177,429, 1,311,884, 1,338,799, 1,385,371, 1,467,214, 1,433,102 and 1,553,516, JP-A-48-85130, JP-A-49-114420, JP-A-50-147712, JP-A-55-161233, JP-A-58-143342, JP-A-59-38742, JP-A-59-111641, JP-A-59-111640, and U.S. Pat. Nos. 3,247,127, 3,469,985 and 4,078,933; other oxonol dyes disclosed, for example, in U.S. Pat. Nos. 2,533,472 and 3,379,533, and British Patent 1,278,621; azo dyes disclosed, for example, in British Patents 575,691, 680,631, 599,623, 786,907, 907,125 and 1,045,609, U.S. Pat. No. 4,255,326, and JP-A-59-211043; azomethine dyes disclosed, for example, in JP-A-50-100116, JP-A-54-118247 and British Patents 2,014,598 and 750,031; anthraquinone dyes disclosed in U.S. Pat. No. 2,865,752; arylidene dyes disclosed, for example, in U.S. Pat. Nos. 2,538,009, 2,688,541 and 2,538,008, British Patents 584,609, 1,210,252, JP-A-50-40625, JP-A-51-3623, JP-A-51-10927, JP-A-54-118247, JP-B-48-3286 and JP-B-59-37303; styryl dyes disclosed, for example, in JP-B-28-3082, JP-B-44-16594 and JP-B-59-28898; triarylmethane dyes disclosed, for example, in British Patents 446,583 and 1,335,422, and JP-A-59-228250; merocyanine dyes disclosed, for example, in British Patents 1,075,653, 1,153,341, 1,284,730, 1,475,228 and 1,542,807; and cyanine dyes disclosed, for example, in U.S. Pat. Nos. 2,843,486 and 3,294,539. (The terms "JP-A" and "JP-B" as used herein signify an "unexamined published Japanese patent application" and an "examined Japanese patent publication" respectively.)
From among these dyes, while oxonol dyes having two pyrazolone nuclei have the property of being decolorized in developers which contain sulfite, they have little adverse action on photographic emulsions and they have therefore been used as useful dyes for light-sensitive materials.
However, even though such dyes have little effect on the photographic emulsion itself, some of these dyes provide spectral sensitization of a spectrally sensitized emulsion in an unsuitable spectral region and also have a disadvantage that results in reduction of photographic sensitivity, apparently caused by decolorization of the sensitizing dyes.
Furthermore, residual coloration remains after processing using such dyes as a result of faster development processing rates which have been used in recent years. The use of dyes which have a higher reactivity with sulfite ion has been proposed as a means of overcoming this problem, but in such cases the stability in the photographic film becomes unsatisfactory, a reduction in density occurs with the passage of time and the prescribed photographic effect is not obtained.
Additionally, when the colored layer is a filter layer or an anti-halation layer located on the same side of the support as the photographic emulsion layer, it is generally required that the layers be selectively colored and spreading of the coloration to other layers prevented. Failure to meet these requirements results in reduced efficiency of the colored layer as a filter layer or anti-halation layer and adverse spectral actions on the other photographic emulsion layers. There are various methods of selectively coloring a specified hydrophilic colloid layer, but, most frequently, methods are used wherein a hydrophilic polymer, containing a portion oppositely charged to that of the dye ion, is included in a hydrophilic layer as a mordant. Such polymers are included in specified emulsion layers having the dye localized by the interaction between the polymer and the dye molecule (due to an attraction by the charge and hydrophobic bonding).
However, when such a mordanting method is used, some of the dye frequently diffuses from the layer to which it has been added to another hydrophilic layer when the layers are in contact under wet conditions such as during processing. Such diffusion of the dyes depends on the chemical structure of the mordant, but it also depends on the chemical structure of the dye which is being used.
Furthermore, residual coloration of the light-sensitive material after photographic processing, and especially after photographic processing with shortened processing times, is likely to occur when a macromolecular mordant is used. This is thought to be due to the fact that, although the bond strength between the mordant and the dye becomes weaker in an alkali solution such as a developer, the bond strength remaining is sufficient to cause the dye or reversible decoloration products to remain in the layer which contains the mordant.
Furthermore, the inclusion of dyes, as disperse solids, is known as another means of retaining the dye in a specified layer of a photographic light-sensitive material, as has been disclosed, for example in JP-A-56-12639, JP-A-52-92716, JP-A-55-155350, JP-A-55-155351, JP-A-52-92716, JP-A-63-27838, JP-A-63-197943, European Patents 0015601B1, 0276566A1, 274723, 276566 and 299435, and Published Unexamined International Application No. 1-502912. However, diffusion of these dyes to other layers has been found to occur and, especially when rapid processing is carried out, some residual coloration of the dye remains in the light-sensitive material. Thus, a need exists to provide colored layers in photographic light-sensitive materials that lack the above-described problems of residual coloration, adverse effects on performance, adverse spectral sensitization shifts, and adverse effects on film aging.